1. Field of the Invention
The present invention relates to a system and method for forming RF reflective pathways. In particular, the system and method is for making variably printed radio frequency antennas for radio frequency tags.
2. Description of the Background Art
Various printing arrangements for forming antennas are known. However, variable demand printing for forming electrically conductive pathways or antennas is not known.
One known method is from U.S. Pat. No. 4,265,703 to Terliska, the entire contents of which are hereby incorporated by reference. In this patent, a method of preparing a fibrous structure containing metallic fibers is disclosed. Other patents to Greene U.S. Pat. Nos., 5,204,681, 5,291,205 and 5,581,257 disclose different radio frequency automatic identification systems. These patents try to detect small resonating particles using an interrogating RF signal.
A resonating pattern can be chosen for an item to be labeled. This pattern can be a designation for the item such as a barcode or it can be a random pattern which is to be assigned to a database for later confirmation. In a barcode situation, each barcode is associated with a particular product. Likewise, a resonating pattern can be chosen according to the product being labeled. In this case, an identification tag may be created which has a random but known response associated with it so that future scanning of that pattern can be associated with the item labeled. Advantages of using a resonating pattern system over current, widely used barcode system is the ability to read in non-line of sight situations, the ability to read through dirt, soiling, etc. on the surface and the possibility of extending automation by not requiring human alignment of the reading system.
Accordingly, it is an object of the present invention to provide a method and system to produce variable on-demand printing of radio frequency reflective (hereinafter RF reflective) pathways. Such pathways can be used to form antennas for radio frequency tags. Two different methods can be utilized for forming such conductive pathways.
In one of these methods, the following steps are carried out: providing a thermal transfer ribbon, moving the thermal transfer ribbon past a heat source, engaging the thermal transfer ribbon with a receiver substrate as the thermal transfer ribbon moves past the heat source, selectively heating portions of the thermal transfer ribbon with the heat source, and transferring a composition from the thermal transfer ribbon to the receiver substrate, the selective heating enabling a desired pattern of the composition to be transferred to the receiver substrate, the composition including a RF reflective material.
In another method for forming RF reflective pathways, the following steps are carried out: providing a substrate coated with reactive material, moving the substrate past a heat source, selectively heating portions of the substrate with the heat source, and developing the reactive material on the substrate during exposure to heat from the heat source to develop a desired pattern on the substrate, the reactive material becoming a RF reflective material.
Further, it is an object of the present invention to also provide a system for producing radio frequency tags comprising a conveyor for moving a substrate, a thermal print head, the conveyor moving the substrate past the thermal print head, the thermal print head being selectively actuatable to heat a desired pattern on the substrate, means on the substrate for reacting with the heat source to form RF reflective pathways, the means including a heat sensitive composition on the substrate.
Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.